In recent years mechanical switches have been replaced by elastomer keypads in applications where longevity of the keys in the keypad as well as aesthetic considerations are important. One application for elastomer keypads is providing control keys for appliances. Elastomer keypads are typically made from a pliable material such as silicon rubber and are mounted over a circuit on a substrate, such as a printed circuit board. The circuit may be defined by two conductive lines or a conductive surface separated by a small distance. Each elastomer key in the elastomer keypad is a raised portion that can be manually depressed. After the elastomer key is released, it will return to its original non-depressed state. The underside (in relation to the raised portion where the elastomer key is depressed) of the elastomer key typically includes a conductive element. This conductive element is made of a conductive material such as carbon. The elastomer keypad is placed over the substrate such that the conductive element in each elastomer key is aligned over the conductive lines. When the elastomer key is depressed, it will deform by flexing inward, resulting in the conductive element contacting both of the conductive lines thereby completing the circuit connection between the conductive lines.
Typically a bezel having openings for each elastomer key to pass through is mounted over the elastomer keypad. This keeps the elastomer keys in the correct position over the substrate. The openings of the bezel are designed to be larger than all parts of the elastomer keys to avoid having the elastomer keys stick or bind to the opening of the bezel. However, because of this loose fit, dirt or moisture can penetrate between the elastomer key and the bezel opening. This can lead to poor performance and/or deterioration of the elastomer key.
Additionally, since the elastomer keys in an elastomer keypad return to their original shape after being depressed, it is often times difficult to determine the status of the machine or appliance it is mounted on after an elastomer key is depressed.